1. Field of the Invention
The present invention concerns a rotating single-phase electromagnetic actuator.
2. Related Art
The state-of-the-art encompasses numerous types of rotating single-phase actuators comprising a stationary device consisting of a first magnetic stator circuit made of a very high-permeability magnetic material excited by at least one trip coil and a movable device formed by an axially-magnetized disk. This magnetic disk has 2N pairs of magnetic poles magnetized in alternating directions. Magnetization is virtually uniform. The magnetized disk is coupled to a second circuit made of a high-permeability material. The movable device is equipped with a coupling shaft designed to transmit torque.
As an example, actuators of this kind are described in Applicant's French Patent (No. 8908052).
Because of miniaturization of actuators and of the precision and reliability required for the majority of real life applications, the positioning of the movable device is critical. Consequently, various mechanical solutions allowing the precise positioning of the shaft and/or rotor have been proposed as part of the art. The principle consistently underlying these solutions lies in reducing the play between the shaft and an actuator-assembly structure as much as possible.
These solutions entail different problems. First, these solutions are expensive, since they require the use of high-precision mechanical systems forming movable parts subject to wear and thus possibly reducing the life and/or reliability of the actuator thus produced.
Moreover, the solutions known in the prior art produce significant rigidity of the unit. Now, actuators are designed to be coupled to mechanical assemblies which may be off-center or have various alignment defects. The absence of any flexibility intrinsic to the actuator thus dictates, in some cases, the use of flexible couplings whose space requirement and cost price may pose problems.
The purpose of the present invention is to solve these difficulties by proposing a solution proving surprising and unexpected results to the specialist who is a person skilled in the art.